Car Combat games, although aside from Twisted Metal they were not that big hell even TM wasn't that big as Half Life or GT.

A lot of these answers have been way off. People aren't thinking hard enough. Declining is not the same as dying. If there's any genre that's dying, it's the Adventure genre. Sure, Zelda is as popular as ever, but that's a given. Besides that, there haven't been many successful Adventure games lately. There was Uncharted, but that was a mix of a couple different genres. And no adventure game lately has sold like Myst or the old Tomb Raider games sold.

There's been a lot of Adventure games.  But now they're just classified as 'Action/Advenutre'.  And as such, get lumped mostly into the 'Action' genre.  Especially now that mosto f them are 3D and focus less on puzzle solving or exploration and more on fighting.  I mean, you could even classify God of War or Shadow of the Collosus as 'Adventure' games.  But most would classify them as something else (mostly 'action adventure').

Well you do have to limit your genres somewhere. RPGs can be Japanese, J turn based, action and probably more there is a wide variety of genres, and since survival games and horror games generally overlap, they get lumped together

Rhythm games that don't use special peripherals. There seems to be a few for handhelds, but absolutely nothing on consoles. Am I right in saying there's been no non-peripheral rhythm/music games for current gen consoles? Those are some of my favorite games. I guess i'm being too specific though.

By rhythm/music games, I mean stuff like Parappa the Rappa, UmJammer Lammy, Space Channel 5, Amplitude, Frequency, Gitaroo Man, etc.

Honestly, if your genre can't survive without hybrids, it's probably already dead. The Platformer genre is still successful because a pure platformer like Super Mario Galaxy can sell well. It's not true with Adventure games.

Actually it seems to me that adventure games were split between Action and ARPG depending on how elaborate/involved the story is.

there are more JRPGs released here in Japan then abroad but i agree the amount on Xbox and PS3 are lean this generation, but more on WII and on handhelds

No (japanese) naughty games on Consoles? (lots of those on PC and a few on PS2)
i haven't seen a romantic game on Xbox360 or PS3 while ON PS2, Handhelds there are many.

On Platformers i have to disagree. LBP is a great new franchise.
Maybe realistic racers? the only new one will Be GT5 (and forza) while a lot are more arcade racers like Midnight club

Race Pro came out on xbox 360 this year. Pretty realistic racer...too realistic actually. The problem with that market is that the games are played for over 100 hours...hence there really is no need for one ever month...unlike FPS games.